The visibility from the cockpit can be recorded;
1. On the Operational flight plan;
2. On the CVR; and
3. Via the R/T to the tower.
I would always use 3 because, it is a doubble edged sword - We are telling the tower that the actual conditions are different from the reported RVR and this could be because they are better or they are worse, and in the case of the 90m visual segment - if only just get it or fail to get it when the reported RVR is 125m, the following landing aircraft and departing aircraft might welcome this information. (R/T tapes are stored for 30 days along with strips).
Anyway provided that the procedure is complied with, how would the CAA prove that the visial segment did not exist?
There is an approach ban procedure - Is there a take-off ban?
Regards,
DFC